Drinking mug



FIG. 1 is a top perspective view of a drinking mug showing my new design;

FIG. 2 is a top plan view thereof on an enlarged scale;

FIG. 3 is a side elevational view thereof;

FIG. 4 is a front elevational view thereof; and

FIG. 5 is a rear elevational view thereof. 

The ornamental design for a drinking mug, as shown. 